1. Field of the Invention
This invention relates to disposable protective caps for use on medical instruments. More particularly, the invention relates to a disposable protective cap for use on spectral imaging devices.
2. Related Art
An important aspect of diagnosing health problems is the ability to analyze and test a subject""s tissue and blood. Non-invasive analysis of a subject""s tissue and blood is advantageous because it does not involve a high risk of injury caused by the testing procedure itself. For example, non-invasive analyses typically avoid puncturing body parts or changing bodily functions, e.g. blood flow, infection levels, vital signs, etc.
Typically, a spectral imaging apparatus is used for non-invasive analysis of a subject""s tissue and blood. The spectral imaging apparatus has a probe with a polarized light source. The probe is used to project an illumination pattern within a region of interest and beneath a surface of the region of interest. A spectral imaging apparatus of this type can be used for measuring and testing. For example, hemoglobin levels can be measured using the spectral imaging apparatus to aid in diagnosing anemia and other diseases involving abnormal red blood cell count. The spectral imaging apparatus can also be used for analysis based solely upon imaging the region of interest. For example, the apparatus can be used to obtain images of tissues to be analyzed by an expert. The expert can use these images to determine the presence of cancerous cells within a particular region.
Using a spectral imaging apparatus to probe a variety of subjects requires the use of a probe cover. The cover, or probe cap, must not block or interfere with the illumination pattern which the probe projects. In order to avoid interference with the illumination pattern, the cap has a window at its end which transmits light. The window is said to have a low birefringence. Low birefringence of the window ensures that the optical properties of the probe will be substantially unaffected by the cap.
It is of critical importance that a cap be used. The same spectral imaging apparatus is typically used on a variety of subjects. The cap reduces the likelihood of spreading contagious diseases from one patient to the next. Without the cap, the probe could contact dangerous viruses and other infectious materials in one subject and transmit them to another subject. For that reason, it is important that the cap be made for disposable use. In addition, it is important that the same cap is not used on more than one subject in order to avoid contamination of the subject and degrade optical performance that can adversely affect the analysis. Beyond the risk of transmitting disease, inaccurate results based erroneously on a different subject""s blood or tissues could dangerously lead to the wrong diagnosis.
Although a conventional probe cap can be made disposable, it is the user of the apparatus who must remember to actually dispose of the conventional cap after each use. During the course of a busy day of testing, even the most cautious user can make the mistake of forgetting to dispose of the probe cap. Even just one such error, on any given day, risks great harm to all subjects being tested with a used cap.
What is needed, therefore, is a disposable probe cover that is easy to install and remove and cannot be accidentally reused.
The present invention is a disposable protective cap for covering a probe for a spectral imaging apparatus. The cap protects the probe from direct contact with a subject""s tissues. The cap is hollow and elongated to cover the probe, having an open end and a closed end. An optically transparent face is located at the closed end. This permits light to be transmitted from the probe through the closed end of the cap with minimal optical distortion. At the open end, the cap includes components which interact with the probe to assure that the cap is not used more than one time. In some embodiments, these components interact electrically to assure only a single disposable use of the cap. In other embodiments, this is accomplished through mechanical interaction. A combination of electrical and mechanical interaction is used in other embodiments to assure only a single use of the cap.
The probe cap of the present invention advantageously avoids the serious health and contamination risks associated with using conventional probe caps. Instead of relying on a lack of human error as is done using conventional probe caps, this invention includes components on the cap to assure only a single disposable use. The present invention will not permit a spectral imaging apparatus to become operable with a used cap on the probe. The components on the probe cap of the present invention interact with the probe electrically, mechanically, or both to ensure that the probe only operates with a new cap.